CN114812514B - Tidal bore tide head line form and tide head propulsion speed on-site measurement method - Google Patents
Tidal bore tide head line form and tide head propulsion speed on-site measurement method Download PDFInfo
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Abstract
The invention relates to a tidal bore head line form and tidal bore head advancing speed field measurement method, which comprises the steps of carrying a high-resolution camera on an unmanned plane to the upper part of tidal bore to photograph the tidal bore head at intervals, so as to obtain a tidal bore head image of the whole measurement river reach; correcting the tidal bore tide head image, and converting the tidal bore tide head image into a unified coordinate system to form a complete tidal bore tide head line orthographic image moment by moment; according to the obvious boundary characteristics of the tidal bore tide head line position, the position of the tidal bore tide head line in the orthophoto image is identified, and the tidal bore tide head line plane position is analyzed from moment to moment; the tide head advancing speed can be obtained according to the tide head line position at the front and rear moments. Can obtain the integral plane form of the tidal bore tide head line and the tidal bore tide head propelling speed in a wide-coverage, high-efficiency and disposable way, is beneficial to analyzing the tidal bore tide propelling speed of the beach and the main groove, the method provides technical support for public safety tide observation, can analyze the impact effect of the tide on the river reach, and has important significance for the construction and protection of the tide river reach.
Description
Technical Field
The invention belongs to the technical field of tidal bore on-site measurement methods, and particularly relates to a tidal bore head line form and tidal bore head propulsion speed on-site measurement method.
Background
The tidal bore tide head forms various plane lines such as cross, first line tide, returning tide and the like in the forward advancing process of the river channel, the plane geometric form of the tidal bore tide head line, the advancing speed of each point along the tidal bore tide head line are closely related to the tidal bore tide height, the water depth before tide, the underwater topography and the like, and the tidal bore tide form and the advancing speed of the tidal bore tide head line are important research contents of tidal bore tide research. Due to the restrictions of observation technology and observation conditions, the method mainly comprises near-shore fixed-point observation and shoreside photographing, and only the average advancing speed of the shoreside tidal bore line can be observed, the instantaneous advancing speed of the whole tidal bore line along the line is lacking, and the overall plane geometry of the tidal bore line cannot be quantitatively analyzed. The method adopted by the patent can quantitatively analyze the plane geometry of the tidal bore tide head line, the advancing speed Ci of each point along the whole tide head line is obtained, provides on-site tidal bore observation results for tidal bore research and is used for the research of tidal bore power and morphological development and change processes. The method can be used for analyzing the impact effect of a river reach of tidal bore on structures such as embankments, spur dams, bridges, wharfs and the like by on-site measurement of the plane shape, the propelling speed and the propelling direction of the tidal bore, can be used as a tidal bore monitoring technology, can also be used for observing and early warning tidal bore movement during tidal bore observation, and provides technical support for public tidal bore observation safety.
The foregoing background knowledge is intended to assist those of ordinary skill in the art in understanding the prior art that is closer to the present invention and to facilitate an understanding of the inventive concepts and aspects herein, and it should be understood that the foregoing background art should not be used to assess the novelty of the present application without explicit evidence that such disclosure is already disclosed prior to the filing date of the present application.
Disclosure of Invention
The invention aims to provide a tidal bore tide head line shape and tide head advancing speed on-site measuring method, can obtain the integral plane shape of the tidal bore tide head line, different space positions and the tidal bore tide head propelling speeds at different moments in a wide-coverage, high-efficiency and one-time way, the tidal flat and main groove tidal bore advancing speed analysis is facilitated, technical support is provided for public tidal bore observation safety, impact effect of tidal bore sections on structures such as embankments, spur dams, bridges and wharfs can be analyzed, and the tidal flat and main groove tidal bore advancing speed analysis has important significance for construction and protection of tidal bore sections.
In order to achieve the above object, the present invention provides the following technical solutions.
A tidal bore tide head line shape and tide head advancing speed field measuring method comprises the following steps:
step 1: an unmanned plane is adopted to carry a high-resolution camera, a GPS (global positioning system) positioning instrument and a distance meter to the position above the tidal bore, and the tidal bore head is photographed at intervals of delta t to obtain a tidal bore head image of the whole measurement river reach;
step 2: correcting the tidal bore tide head image, converting the processed image into a unified coordinate system according to camera parameters to form a complete tidal bore head line orthographic image moment by moment;
step 3: according to the obvious boundary characteristics of the tidal bore tide head line position, the position of the tidal bore tide head line in the orthographic image is identified through a boundary identification technology, and the tidal bore tide head line plane position is analyzed from moment to moment;
step 4: the tide head advancing speed can be obtained according to the tide head line position at the front and rear moments.
Further, in step 1, at least one unmanned aerial vehicle is provided.
In the step 1, further, the tidal bore tide head image of the whole measurement river reach can be obtained by splicing after segmented photographing and obtaining in a mode of collaborative photographing by a plurality of unmanned aerial vehicles.
Further, in step 1, the unmanned aerial vehicle hovers at a fixed point position and keeps the main optical axis of the camera vertical to the ground (water surface), the camera is started to take a picture, space positioning is performed through the GPS while taking a picture, a distance meter is used for measuring the distance between the unmanned aerial vehicle and the water surface, and camera shooting parameters are obtained according to the installation relative relation between the camera and the GPS as well as the distance meter.
In step 1, before photographing and measuring, calibrating the camera, determining a distortion correction calculation parameter, and correcting the image by using the parameter.
Further, in the step 2, the correction of the tidal bore head image comprises image radial distortion correction and image tangential distortion correction.
Further, the image radial distortion correction formula is as follows:
x 0 ＝x(1+k 1 r 2 +k 2 r 4 +k 3 r 6 )
y 0 ＝y(1+k 1 r 2 +k 2 r 4 +k 3 r 6 )
in the formula, (x) 0 ，y 0 ) Is the original pixel position of the distortion point on the original image, (x, y) is the pixel position on the new image after correction, k 1 、k 2 、k 3 Is a distortion correction calculation parameter related to the camera lens.
Further, the formula for correcting the tangential distortion of the image is as follows:
x 0 ＝x+[2p 1 y+p 2 (r 2 +2x 2 )]
y 0 ＝y+[2p 2 x+p 1 (r 2 +2y 2 )]
in the formula, (x) 0 ，y 0 ) The original pixel position of the distortion point on the original image, (x, y) is the pixel position on the new image after correction, p 1 、p 2 Is a distortion correction calculation parameter related to the camera lens.
The prior art can reduce the perspective distortion to a lower degree, but can not completely eliminate distortion, particularly distortion and distortion of different degrees generated by the edge of a lens, and the distortion of a picture can be corrected to a larger degree due to the fact that the lens is not parallel to a camera sensor plane (imaging plane) or an image plane and tangential distortion is possibly generated, so that the accuracy is improved in subsequent registration and identification.
Further, in step 2, the camera parameters include camera space coordinates, object distance, and distance.
In step 2, the processed image is converted into a unified coordinate system, specifically, the absolute registration and the relative registration of the images are combined, and the photographed images are unified into the same coordinate system.
Absolute registration means that a coordinate system is defined first, and all images are registered relative to the coordinate grid, that is, geometric correction of each component image is completed to realize the unification of the coordinate system, which can be performed by a computer and auxiliary manual method.
The relative registration refers to that one image in multiple images is selected as a reference image, other related images are registered with the reference image, the other related images can be automatically matched through a related algorithm, the coordinate system of the related images is arbitrary, but when the coordinates of the reference image are known, the image after the automatic matching is naturally the same as the coordinate system of the reference image.
Further, converting the processed image into a unified coordinate system specifically includes: and carrying out absolute registration on the first image, carrying out relative registration on the images shot subsequently by taking the first image as a reference, and carrying out absolute registration on the images registered by the process, wherein the images have the same coordinate system as the first image, so that the absolute registration is realized.
Furthermore, a fixed object is selected for relative registration, and an object with position change or deformation in the shooting process cannot be used for relative registration.
Further, in step 3, the specific step of identifying the position of the tidal bore head line in the orthophoto image by the boundary identification technology is as follows:
firstly, reading a picture into a tide line identification module, and converting an original color picture into a gray picture, wherein the conversion formula is as follows:
Gray＝0.299R+0.887G+0.114B
gray represents a Gray image, and RGB represents three channel Gray values of red (red), green (green) and blue (blue) of a color image;
detecting and identifying edges by adopting a Canny operator, wherein the Canny operator adopts Gaussian filtering, and the mode is as follows:
and (3) calculating the image gradient, non-maximum value inhibition and double-threshold value screening through Gaussian filtering, and performing edge connection treatment to obtain the object edge, thus obtaining the tidal bore head line.
Further, the gaussian filter is:
further, in step 4, the advancing speed of the tide head includes the advancing speed of the tide head at each point on the tide head line, the advancing speed of the whole tide head line, and the advancing speed of the tide head line at each moment.
Further, in step 4, the specific step of obtaining the advancing speed of the tide head according to the position of the tide head line at the front and rear moments is as follows: all the images are converted into an actual coordinate system, after the tidal bore tide head line identification at each moment is completed, can be used for curing any point P on the tide line the push speed of the tidal bore tide head at the position is calculated, let t i Time sum t i+1 The tidal bore tide head lines are overlapped together at the moment, tidal bore head advancing speed C at point P i ＝dS i /(t i -t i+1 ) The propulsion speed of the tide head line at each point on the tide head line is calculated by adopting the same method, so that the propulsion speed distribution of the whole tide head line can be obtained, and the propulsion speed of the tide head line at each moment is calculated by adopting the same method.
The time and tidal bore speed of each point in the tidal bore reaching the river reach can be calculated by combining the advancing speed of each point of the tidal bore line and the condition of the known tidal bore not reached, so that the observation and early warning of the tidal bore movement during the tidal bore observation are facilitated, technical support is provided for public tidal bore observation safety, the impact effect of the river reach of the tidal bore on structures such as embankment, spur dike, bridge and wharf can be analyzed accordingly, and the method has important significance for the construction and protection of the dike, the water bottom and the like of the tidal bore river reach.
The above-mentioned preferable conditions can be combined with each other to obtain a specific embodiment on the basis of common knowledge in the art.
The beneficial effects of the invention are as follows:
carrying a high-definition camera on an unmanned plane to measure the tidal bore plane geometry and the tidal bore line advancing speed, (1) having wide coverage and high measuring efficiency, and obtaining the tidal bore line overall plane shape at one time; (2) simultaneously acquiring the advancing speed of the tide head at each position of the tide head line; (3) The tidal bore head propulsion speeds of different spatial positions are obtained, so that tidal flat ground tidal bore propulsion speed analysis of the main tank is facilitated; (4) Shooting can be tracked, and shooting measurement can be performed when tidal bore moves to and the tidal bore moves to; (5) The actual measurement is convenient, the implementation is flexible, the unmanned aerial vehicle measurement is not limited by the position, the measurement can be flexibly carried out, the observation can be carried out on a fixed river reach, and the observation can be carried out on a temporary needed measurement river reach; (6) Calculating the time for tidal bore to reach each point in the river reach and the tidal bore speed, facilitating the observation and early warning of tidal bore movement during tidal bore observation and providing technical support for public tidal bore observation safety; (7) The impact of the tidal bore river reach on structures such as embankments, spur dams, bridges, wharfs and the like can be analyzed, and the method has important significance for construction and protection of the tidal bore river reach such as dykes and dams, water bottoms and the like.
The invention adopts the technical proposal to realize the aim, makes up the defects of the prior art, has reasonable design and convenient operation.
Drawings
The foregoing and/or other objects, features, advantages and embodiments of the invention will be apparent from the following description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic view of a multi-shot tidal bore;
FIG. 2 is a tidal bore diagram;
FIG. 3 is a schematic diagram of absolute registration coordinate transformation;
FIG. 4 is a schematic diagram of a tidal bore head identification process;
FIG. 5 is a schematic view of a tidal head line;
fig. 6 is a schematic view of the calculation of the tidal head line advancing speed.
Detailed Description
Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The present invention uses the methods and tools described herein; other suitable methods and tools known in the art may be used. The tools, methods, and examples described herein are illustrative only and not intended to be limiting. All publications, patent applications, patents, provisional applications, database entries, and other references mentioned herein, and the like, are incorporated herein by reference in their entirety. In case of conflict, the present specification, including definitions, will control.
The tools, methods, and examples described herein are illustrative only and not intended to be limiting unless specifically indicated. Although methods and tools similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and tools are described herein.
The present invention is described in detail below.
Example 1:
the method for measuring the form of a tidal bore tide head line and the advancing speed of the tide head on site adopts an unmanned plane to carry a high-resolution camera, a GPS (global positioning system) positioning instrument and a range finder to the upper part of the tidal bore tide, and photographs the tidal bore tide head at intervals of delta t to obtain a tidal bore tide head image of the whole measurement river reach, and specifically comprises the following steps:
as shown in fig. 1 and 2, a method of taking photos by using an unmanned aerial vehicle to carry a high-resolution camera, positioning by using a GPS (global positioning system) and measuring by using a range finder is adopted, the camera is calibrated before taking photos and measuring, distortion correction calculation parameters are determined, when a tidal bore comes, the unmanned aerial vehicle D1 flies above the tidal bore, hovers at a fixed point position and keeps a main optical axis of the camera vertical to the ground (water surface), the camera is started to take photos according to a fixed time interval delta t, space positioning is carried out by using the GPS while taking photos, the distance between the distance meter and the water surface is measured, and camera shooting parameters are obtained according to the installation relative relation between the camera, the GPS and the range finder.
When the tidal bore tide head line is about to move out of the photographing range, the unmanned aerial vehicle D2 with the same configuration can be flown to the next observation point in advance to carry out the same observation, the overlapping area of the photographed photo of the D2 and the registered photo is registered relatively, after the registration is completed, the photo photographed in the later stage of the D2 is registered with the registered photo, the splicing dislocation is reduced, and the photo has the same coordinate system. If all of D1, D2 and … … are taken with absolute coordinates, an error is unavoidable between the absolute coordinates, so that the taken photo deviates, and therefore, the splicing dislocation can be greatly reduced and the measurement accuracy can be improved by adopting absolute registration and relative registration for photo registration.
Likewise, when the tidal head line is about to move out of the shooting range of the D2 camera, a third unmanned aerial vehicle can lift off to shoot in a relay mode, and the fourth unmanned aerial vehicle and the fifth unmanned aerial vehicle are similarly operated, until the unmanned aerial vehicle shooting range can cover the whole tidal bore head line at the same time, and when a plurality of unmanned aerial vehicles shoot, the shooting time intervals are kept the same, and the shooting time is synchronous.
Example 2:
because of the image distortion caused by perspective reasons in the imaging process of a camera, the photo is subjected to distortion correction before registration and identification, the tidal bore head image is corrected on the basis of the embodiment, and the processed image is converted into a unified coordinate system according to camera parameters (including camera space coordinates, object distances and distances) to form a time-to-time complete tidal bore head line orthographic image, which comprises the following steps:
(1) Image radial distortion correction:
the prior art camera technology can reduce perspective distortion to a lower degree, but can not completely eliminate distortion, particularly distortion and distortion of different degrees generated by the edge of a lens. The distortion correction formula applied in this embodiment is as follows:
x 0 ＝x(1+k 1 r 2 +k 2 r 4 +k 3 r 6 )
y 0 ＝y(1+k 1 r 2 +k 2 r 4 +k 3 r 6 )
in the formula, (x) 0 ，y 0 ) Is the original pixel position of the distortion point on the original image, (x, y) is the pixel position on the new image after correction, k 1 、k 2 、k 3 Is a distortion correction calculation parameter related to the camera lens.
(2) Correction of tangential distortion of an image:
tangential distortion is generated by the lens itself being non-parallel to the camera sensor plane (imaging plane) or image plane, and the correction formula is as follows:
x 0 ＝x+[2p 1 y+p 2 (r 2 +2x 2 )]
y 0 ＝y+[2p 2 x+p 1 (r 2 +2y 2 )]
in the formula, (x) 0 ，y 0 ) The original pixel position of the distortion point on the original image, (x, y) is the pixel position on the new image after correction, p 1 、p 2 Is a distortion correction calculation parameter related to the camera lens.
Example 3:
on the basis of the foregoing embodiment, the converting the processed image into a unified coordinate system, specifically, combining the absolute registration and the relative registration of the images, unifies the photographed images into the same coordinate system, specifically includes:
(1) Absolute registration of the first picture:
as shown in fig. 3, two translation parameters dx, dy in the x, y direction and a rotation parameter θ around the perpendicular to the plane are required for the transformation in the two-dimensional plane, and furthermore, there is a scaling factor m, the specific transformation relationship is as follows:
in the middle of
For controlling the coordinate vector of the feature point in the XOY coordinate system (actual coordinate system)>
For controlling the coordinate vector of the feature point under the X ' O ' Y ' frame (pixel frame).
And converting the coordinate system by taking the pixel coordinate system as an original coordinate system and taking the actual coordinate system as a target coordinate system. The coordinates of the control points P1, P2 in the XOY coordinate system (target coordinate system) are known as (x) 1 ，y 1 )、(x 2 ，y 2 ) The coordinates in the X 'O' Y 'coordinate system (original coordinate system) are (X' 1 ，y′ 1 )、(x′ 2 ，y′ 2 )。
Firstly, translating an original point of a coordinate system to P1, wherein the translated coordinate system is X 'O' Y ', the coordinates of P1, P2 at the new coordinates X "O" Y "are (0, 0), (X' 2 -x′1，y′ 2 -y′ 1 ) I.e., the P1 point is located at the X "O" Y "origin. At this time, translational parameters dx and dV, rotation parameters θ and scale ratio parameters m can be obtained by direct calculation. The specific formula is as follows:
translation parameters:
rotation parameters:
scale ratio parameters:
solving the four parameters can realize the transfer from the original coordinate system to the target coordinate.
(2) Relative registration is performed on the rest of the pictures:
after the absolute registration of the first image is completed, the relative registration of the rest images shot later relative to the first image is carried out, and the images registered through the process have the same coordinate system as the first image, so that the absolute registration is realized. It should be noted that the relative alignment is performed by selecting a fixed object (e.g., a bank), and an object (e.g., a float, a ship, or a water surface spray) that changes or deforms during the shooting process cannot be used for the relative alignment.
The image relative registration is to extract the characteristics of two images, find the matched homonymy points (characteristic point pairs) by carrying out similarity measurement, obtain the image space coordinate transformation parameters by the matched homonymy points, and finally carry out image registration by the coordinate transformation parameters. The relative registration is typically fitted to the translation, rotation and affine transformation between the two images by a suitable polynomial. The feature-based method is adopted to determine Registration Control Points (RCPs), obtain image registration function mapping relations and determine coefficients in a transfer polynomial, and various documents exist for image matching algorithms, which are not described in detail herein.
Example 4:
based on the previous embodiment, according to the obvious boundary characteristics of the tidal bore tide head line position, the position of the tidal bore tide head line in the orthographic image is identified by the boundary identification technology, and analyze the position of the tide line plane from time to time, as shown in fig. 4 and 5, specifically including:
firstly, reading a picture into a tide line identification module, and converting an original color picture into a gray picture, wherein the conversion formula is as follows:
Gray＝0.299R+0.887G+0.114B
gray represents a Gray image, and RGB represents three channel Gray values of red (red), green (green) and blue (blue) of a color image;
detecting and identifying edges by adopting a Canny operator, wherein the Canny operator adopts Gaussian filtering, and the mode is as follows:
and (3) calculating the image gradient, non-maximum value inhibition and double-threshold value screening through Gaussian filtering, and performing edge connection treatment to obtain the object edge, thus obtaining the tidal bore head line.
Further, the gaussian filter is:
example 5:
based on the foregoing embodiment, the specific steps for obtaining the tide head advancing speed according to the tide head line position at the front and rear moments are as follows: as shown in FIG. 6, all the images are converted into an actual coordinate system, after the tidal bore head line identification at each moment is completed, the tidal bore head advancing speed at any point P on the tidal bore head line can be calculated, and t is calculated i Time sum t i+1 The tidal bore tide head lines are overlapped together at the moment, tidal bore head advancing speed C at point P i ＝dS i /(t i -t i+1 ) The propulsion speed of the tide head line at each point on the tide head line is calculated by adopting the same method, so that the propulsion speed distribution of the whole tide head line can be obtained, and the propulsion speed of the tide head line at each moment is calculated by adopting the same method.
The time and tidal bore speed of each point in the tidal bore reaching the river reach can be calculated by combining the advancing speed of each point of the tidal bore line and the condition of the known tidal bore not reached, so that the observation and early warning of the tidal bore movement during the tidal bore observation are facilitated, technical support is provided for public tidal bore observation safety, the impact effect of the river reach of the tidal bore on structures such as embankment, spur dike, bridge and wharf can be analyzed accordingly, and the method has important significance for the construction and protection of the dike, the water bottom and the like of the tidal bore river reach.
The conventional technology in the above embodiments is known to those skilled in the art, and thus is not described in detail herein.
The specific embodiments described herein are offered by way of example only to illustrate the spirit of the invention. Various modifications or additions to the described embodiments may be made by those skilled in the art to which the invention pertains or may be substituted in a similar manner without departing from the spirit of the invention or beyond the scope of the appended claims.
While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.
While the above detailed description has shown, described, and pointed out novel features as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the device or method illustrated may be made without departing from the spirit of the disclosure. In addition, the various features and methods described above may be used independently of one another, or may be combined in various ways. All possible combinations and subcombinations are intended to fall within the scope of this disclosure. Many of the embodiments described above include similar components, and thus, these similar components are interchangeable in different embodiments. While the invention has been disclosed in the context of certain embodiments and examples, it will be understood by those skilled in the art that the invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses and obvious modifications and equivalents thereof. Therefore, the present invention is not intended to be limited by the specific disclosure of the preferred embodiments herein.
The invention is a well-known technique.
Claims (8)
1. A tidal bore tide head line shape and tide head propelling speed field measurement method is characterized by comprising the following steps:
step 1: an unmanned plane is adopted to carry a high-resolution camera, a GPS (global positioning system) positioning instrument and a distance meter to the position above the tidal bore, and the tidal bore head is photographed at intervals of delta t to obtain a tidal bore head image of the whole measurement river reach;
step 2: correcting the tidal bore tide head image, converting the processed image into a unified coordinate system according to camera parameters to form a complete tidal bore head line orthographic image moment by moment;
step 3: according to the obvious boundary characteristics of the tidal bore tide head line position, the position of the tidal bore tide head line in the orthographic image is identified through a boundary identification technology, and the tidal bore tide head line plane position is analyzed from moment to moment;
step 4: the tide head propelling speed can be obtained according to the tide head line positions at the front and rear moments;
in the step 2, the correction of the tidal bore head image comprises image radial distortion correction and image tangential distortion correction:
the formula of the radial distortion correction of the image is as follows:
x 0 ＝x(1+k 1 r 2 +k 2 r 4 +k 3 r 6 )
y 0 ＝y(1+k 1 r 2 +k 2 r 4 +k 3 r 6 )
in the formula, (x) 0 ,y 0 ) Is the original pixel position of the distortion point on the original image, (x, y) is the pixel position on the new image after correction, k 1 、k 2 、k 3 Is a deformation correction calculation parameter related to the camera lens;
the formula of the tangential distortion correction of the image is as follows:
x 0 ＝x+[2p 1 y+p 2 (r 2 +2x 2 )]
y 0 ＝y+[2p 2 x+p 1 (r 2 +2y 2 )]
in the formula, (x) 0 ,y 0 ) The original pixel position of the distortion point on the original image, (x, y) is the pixel position on the new image after correction, p 1 、p 2 Is a deformation correction calculation parameter related to the camera lens;
in step 2, converting the processed image into a unified coordinate system to form a complete tidal bore head line orthophoto image moment by moment specifically comprises: absolute registration is carried out on the first image, the images shot subsequently are subjected to relative registration by taking the first image as a reference, and the images subjected to the process registration have the same coordinate system as the first image, so that the absolute registration is also realized;
when the tidal bore tide head line is about to move out of the photographing range, the unmanned aerial vehicle D2 which is configured in the same way can be flown to the next observation point in advance to carry out the same observation, the overlapping area of the photo shot by the D2 and the first unmanned aerial vehicle D1 is registered relatively, after the registration is completed, the photo shot at the later stage of the D2 is registered with the registered photo, the splicing dislocation is reduced, and the photo has the same coordinate system;
when the tidal bore line is about to move out of the shooting range of the D2 camera, the third unmanned aerial vehicle can lift off to shoot in a relay mode, and the fourth unmanned aerial vehicle and the fifth unmanned aerial vehicle can be similarly used, so that the tidal bore line can be covered simultaneously until the shooting range of the unmanned aerial vehicle, and the shooting time intervals are kept the same and the shooting time is synchronous when the plurality of unmanned aerial vehicles shoot.
2. The method according to claim 1, characterized in that: in the step 1, the tidal bore tide head image of the whole measurement river reach can be obtained by splicing after segmented photographing and obtaining in a mode of collaborative photographing by a plurality of unmanned aerial vehicles.
3. The method according to claim 1 or 2, characterized in that: in step 1, the unmanned aerial vehicle hovers at a fixed point position, enables a main optical axis of a camera to be vertical to the water surface, starts the camera to take a picture, performs space positioning through a GPS (global positioning system) while taking the picture, measures the distance between the unmanned aerial vehicle and the water surface by adopting a range finder, and obtains camera shooting parameters according to the installation relative relation between the camera and the GPS as well as the range finder.
4. The method according to claim 1 or 2, characterized in that: in the step 1, before photographing and measuring, the camera is calibrated, the distortion correction calculation parameter is determined, and the image correction can be carried out by using the parameter.
5. The method according to claim 1 or 2, characterized in that: in step 2, the camera parameters include camera space coordinates, object distance, and distance.
6. The method according to claim 1 or 2, characterized in that: in the step 4, the specific steps of identifying the position of the tidal bore tide head line in the orthophoto image by the boundary identification technology are as follows:
firstly, reading a picture into a tide line identification module, and converting an original color picture into a gray picture, wherein the conversion formula is as follows:
Gray＝0.299R+0.887G+0.114B
gray represents a Gray image, and RGB represents three channel Gray values of red (red), green (green) and blue (blue) of a color image;
detecting and identifying edges by adopting a Canny operator, wherein the Canny operator adopts Gaussian filtering, and the mode is as follows:
and (3) calculating the image gradient, non-maximum value inhibition and double-threshold value screening through Gaussian filtering, and performing edge connection treatment to obtain the object edge, thus obtaining the tidal bore head line.
7. The method according to claim 6, wherein: the gaussian filter is:
8. the method according to claim 1 or 2, characterized in that: in the step 4, the specific steps of obtaining the advancing speed of the tide head according to the position of the tide head line at the front and back moments are as follows: all the images are converted into an actual coordinate system, after the tidal bore tide head line identification at each moment is completed, can be used for curing any point P on the tide line the push speed of the tidal bore tide head at the position is calculated, let t i Time sum t i+1 The tidal bore tide head lines are overlapped together at the moment, tidal bore head advancing speed C at point P i ＝dS i /(t i -t i+1 ) The propulsion speed of the tide head line at each point on the tide head line is calculated by adopting the same method, so that the propulsion speed distribution of the whole tide head line can be obtained, and the propulsion speed of the tide head line at each moment is calculated by adopting the same method.
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